Loopy stitches on the back

Rethread the machine. Its almost always caused by poor quality threads or misthreading.

Sergers are very interesting and complex machines, and you don't have to have something out of whack very much to upset the operation. Check your treading again - make sure it all the treads match the diagrams. Check your needle(s) for burrs at the tip. If in doubt, replace them. Check the needle plate and foot for burrs. Anytime a needle comes in contact with anything but fabric, there's a fair chance something will get a burr. When that happens, the thread doesn't feed properly.

Loopy on bottom means the top tensions need to be adjusted. "All on 3 means nothing" These are tension knobs and are not required to be on the same number.

In the mean time rethread the machine with a different color on each spool This will help you determine which thread is the offender. sew the same type of material this thread set up... tighten the corresponding tension dial. Once you get a good stitch, Lift the food, cut all the threads near the spools and tie off new thread/spools and pull the thread through to the needle. Once it is all threaded again test your stitch with the same fabric again.

Hi

If you have the operators manual for this serger, you should be able to follow the threading from the start successfully. Some machines have a better threading diagram on the machine itself.

The needles should have the groove facing the operator's position. They should also be fully inserted in their mounts. Most sergers do not release the thread tensions when the presser foot is raised, therefore, you must zero the tensions to make sure the threads are fully entered into the tensioners when threading anew. After threading, you must readjust your thread tensions to the desired tensions for the set-up you plan to use. Thread tensions should be recorded for each stitch set-up because each serger tends to be a bit different, and therefore, allows you to quickly adjust for the desired stitch needed. The different stitches are adjust and fine tuned by each individual thread tension.

Hope this helps
Ray

change the needle
rethread the top thread make sure the thread doesn't come off the thread take up lever
check the bobbin area for lint or loose threads
also rethread the bobbin in the bobbin case & reinsert it
also check the top thread tension try 3 or 4

Generally caused by lack of tension on the upper thread. Thread machine normally and pull the needle thread sideways from the needle with the presser foot up. It should pull smoothly. Lower the presser foot and it should become hard to pull and the needle will bend. If this doesn't happen, the upper thread is not in the tension assembly and you should rethread properly. Also, make sure thread is in the take up lever that moves up and down on the front of the machine while sewing.

this is a common problem, don't worry it's easy to fix.  take the spool of thread off, remove the bobbin.  look for any stray thread pieces in or around the bobbin case, rethread the top of the machine and when you do, follow the threading guide precisely and ---here's the trick---make certain that the thread goes between the tension discs.

It's possible that there is foreign debris in the top tension assembly ,thread the machine and lower the presser foot and ensure that there is tension on the top thread

With some sergers, but not many (singer 14u64 comes to mind), the top of the stitch will be an overedge that mates with the right needle thread, and the left needle thread will appear as a separate straight stitch. When you look at the underside of the stitch, the overedge will go all the way over to the left needle (the full width of the stitch). This is normal if you have this type of machine. Another stitch some sergers do (2/4 thread sergers) is a 2 thread chain thal looks like a lone straight stitch on both sides, and a 2 thread separate overedge.

As far as the threading of the takeup, it totally depends on your model. Always post your model number when you have questions as sergers vary greatly in design.